A center rest is typically used to support a long workpiece in a lathe between the headstock and tailstock. It typically has two outer and a center support elements, each having a respective track roller. The rollers all lie in a plane perpendicular the workpiece rotation axis and are rotatable about respective roller axes parallel to, radially equispaced from and generally angularly equispaced about the workpiece rotation axis. The center roller is shiftable in a straight line against the workpiece radially of the workpiece axis. The outer rollers are typically mounted on arms pivoted in axles in a housing of the center rest so that they can move radially of the workpiece center axis, but along arcuate paths centered on the respective axles.
A steady rest of the above-described type that is hydraulically actuated is known from DE 35 44 961 [U.S. Pat. No. 4,754,673]. Care must always be taken that sufficient hydraulic fluid is present in the piston chambers in order to maintain the holding force of the steady rest for holding a cylindrical center portion of the workpiece being turned. Leaks pose a problem for hydraulically actuated steady rests, and result in a loss in holding force.